[ntp:questions] Using NTP to calibrate sound app

no-one at no-place.org no-one at no-place.org
Tue Jan 29 21:39:00 UTC 2013

On 29 Jan 2013 17:43:48 GMT, Rob <nomail at example.com> wrote:

>What I still don't understand is why you cannot just use the local
>clock to do the calibration.  Are you claiming that the devices that
>have the 22150 sample rate also have a local clock that is running
>fast by the same amount?   I would not expect that.  It would mean
>the clock would run fast by 6.5 minutes/day, something that some user
>would certainly notice and rightfully complain about.

The local clock could indeed be used to detect the gross deviation of
4000 ppm.  But that is only the extreme case.  There are other cases
where the deviation is smaller, but still large enough to need
correction.  They are probably where the OEM really intended to
produce 22,050 audio samples per second, but for whatever reason the
result was more than 12 ppm off.

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